Optimized skew in interior permanent magnet synchronous motors

Abstract

A system includes an electric motor, a rotor associated with electric motor, a first pole of the rotor, and a first magnet stack associated with the first pole. The first magnet set includes a set of magnets disposed proximate the rotor arranged according to a skewed arrangement and including at least a first magnet having a first length, a second magnet having a second length, and a third magnet having a third length.

What is claimed is: 
     
         1 . A system comprising:
 an electric motor;   a rotor associated with electric motor;   a first pole of the rotor; and   a first magnet stack associated with the first pole comprising a set of magnets disposed proximate the rotor arranged according to a skewed arrangement and including at least a first magnet having a first length, a second magnet having a second length, and a third magnet having a third length.   
     
     
         2 . The system of  claim 1 , wherein the electric motor includes a permanent magnet synchronous motor. 
     
     
         3 . The system of  claim 2 , wherein the permanent magnet synchronous motor includes an interior permanent magnet synchronous motor. 
     
     
         4 . The system of  claim 2 , wherein the permanent magnet synchronous motor includes a surface mounted permanent magnet synchronous motor. 
     
     
         5 . The system of  claim 1 , wherein the first length is the same as the third length. 
     
     
         6 . The system of  claim 5 , wherein the first length is greater than the second length. 
     
     
         7 . The system of  claim 1 , wherein the first length and the third length are the same as the second length. 
     
     
         8 . The system of  claim 1 , wherein the skewed arrangement includes V-skewed arrangement. 
     
     
         9 . The system of  claim 6 , wherein the V-skewed arrangement includes a six step V-skewed arrangement. 
     
     
         10 . The system of  claim 1 , wherein the electric motor is associated with a steering system of a vehicle. 
     
     
         11 . The system of  claim 10 , wherein the steering system includes an electric power steering system. 
     
     
         12 . The system of  claim 10 , wherein the steering system includes a steer-by-wire steering system. 
     
     
         13 . The system of  claim 1 , wherein the set of magnets further includes a fourth magnet having a fourth length, a fifth magnet having a fifth length, and a sixth magnet having a sixth length. 
     
     
         14 . The system of  claim 13 , wherein the fourth length is the same as the third length, the fifth length is the same as the second length, and the sixth length is the same as the first length. 
     
     
         15 . The system of  claim 1 , wherein the first pole includes a second magnet stack and a third magnet stack. 
     
     
         16 . The system of  claim 1 , wherein the rotor further includes the first pole and at least one other pole. 
     
     
         17 . An electric motor comprising:
 a rotor;   a first pole of the rotor; and   a first magnet stack associated with the first pole comprising a set of magnets disposed proximate the rotor arranged according to a skewed arrangement and including at least a first magnet having a first length, a second magnet having a second length, and a third magnet having a third length, wherein the first length is the same as the third length.   
     
     
         18 . The electric motor of  claim 17 , wherein the second length is the same as the first length and the third length. 
     
     
         19 . The electric motor of  claim 17 , wherein the first length is greater than the second length. 
     
     
         20 . A method for controlling cogging torque of an electric motor, the method comprising:
 providing, at a first magnet stack of a first pole of a rotor associated with the electric motor, a first set of magnets; and   arranging magnets of the first set of magnets according to a six-step V-skewed arrangement, wherein:
 the first set of magnets includes a first magnet having a first axial length, a second magnet having a second axial length, a third magnet having a third axial length, a fourth magnet having a fourth axial length, a fifth magnet having a fifth axial length, and a sixth magnet having a sixth axial length, 
 the first axial length is the same as the third axial length, the fourth axial length, and the sixth axial length, 
 the second axial length is one of the same as the first axial length and less than the first axial length, and 
 the fifth axial length is one of the same as the fourth axial length and less than the fourth axial length.